EP 1 610 018 B1, for example, discloses a friction clutch embodied as a wet-running start-up clutch. The friction clutch comprises an input side and an output side, which are arranged for rotation, as well as an fluid chamber. To transmit a torque between the input side and the output side in a frictional way, first friction discs are provided that are in a torque-locking engagement with the input side and are axially displaceable. Furthermore, second friction discs are provided, which are likewise axially displaceable and are connected to the output side in a torque-locking way. The actuating piston is displaced in an axial direction by a pressure chamber into which a pressure fluid is introduced and compresses the friction discs to establish a torque-locking engagement between the input side and the output side.
Moreover, DE 10 2008 060 577 discloses a torque converter including a friction clutch.
In both cases, the friction clutches are cooled by a cooling liquid provided in a housing of the friction clutch. The cooling liquid absorbs the heat that is generated as the clutch is being engaged to prevent the clutch, in particular the friction discs of the friction clutch, from over-heating.